High performance multi-functional trilayer membranes as permselective separators for lithium–sulfur batteries

Abstract

Multi-walled carbon nanotubes (MWCNTs) and magnesium aluminate (MgAl₂O₄) were coated on either side of a commercially available Celgard 2320 membrane by a simple doctor blade method. This trilayer membrane (TLM) was subjected to ionic conductivity, thermal stability and contact angle measurements. Each layer of the TLM functions for a specific purpose: the MWCNTs provide electronic conductivity while the pores of the Celgard 2320 membrane facilitate lithium-ion transport and MgAl₂O₄ suppresses the shuttling of polysulfides due to the electrostatic attractive force. The TLM exhibited superior thermal stability and ionic conductivity than the uncoated Celgard 2320 membrane. The Li–S cell with a TLM offered a higher discharge capacity than the one with an uncoated membrane. The results are compared with earlier reports.